Feb. 28, 2013
Steve Cole
Headquarters, Washington
202-358-0918
stephen.e.cole@nasa.gov
Laura Catherine Snider
University of Colorado
303-735-0528
laura.snider@colorado.edu
Geoff Brown
Johns Hopkins University Applied Physics Laboratory
240-228-5618 or 443-778-5618
geoffrey.brown@jhuapl.edu
RELEASE: 13-065
NASA'S VAN ALLEN PROBES REVEAL A NEW RADIATION BELT AROUND EARTH
WASHINGTON -- NASA's Van Allen Probes mission has discovered a
previously unknown third radiation belt around Earth, revealing the
existence of unexpected structures and processes within these
hazardous regions of space.
Previous observations of Earth's Van Allen belts have long documented
two distinct regions of trapped radiation surrounding our planet.
Particle detection instruments aboard the twin Van Allen Probes,
launched Aug. 30, quickly revealed to scientists the existence of
this new, transient, third radiation belt.
The belts, named for their discoverer, James Van Allen, are critical
regions for modern society, which is dependent on many space-based
technologies. The Van Allen belts are affected by solar storms and
space weather and can swell dramatically. When this occurs, they can
pose dangers to communications and GPS satellites, as well as humans
in space.
"The fantastic new capabilities and advances in technology in the Van
Allen Probes have allowed scientists to see in unprecedented detail
how the radiation belts are populated with charged particles and will
provide insight on what causes them to change, and how these
processes affect the upper reaches of Earth's atmosphere," said John
Grunsfeld, NASA's associate administrator for science in Washington.
This discovery shows the dynamic and variable nature of the radiation
belts and improves our understanding of how they respond to solar
activity. The findings, published Thursday in the journal Science,
are the result of data gathered by the first dual-spacecraft mission
to fly through our planet's radiation belts.
The new high-resolution observations by the Relativistic Electron
Proton Telescope (REPT) instrument, part of the Energetic Particle,
Composition, and Thermal Plasma Suite (ECT) aboard the Van Allen
Probes, revealed there can be three distinct, long-lasting belt
structures with the emergence of a second empty slot region, or
space, in between.
"This is the first time we have had such high-resolution instruments
look at time, space and energy together in the outer belt," said
Daniel Baker, lead author of the study and REPT instrument lead at
the Laboratory for Atmospheric and Space Physics (LASP) at the
University of Colorado in Boulder. "Previous observations of the
outer radiation belt only resolved it as a single blurry element.
When we turned REPT on just two days after launch, a powerful
electron acceleration event was already in progress, and we clearly
saw the new belt and new slot between it and the outer belt."
Scientists observed the third belt for four weeks before a powerful
interplanetary shock wave from the sun annihilated it. Observations
were made by scientists from institutions including LASP; NASA's
Goddard Space Flight Center in Greenbelt, Md.; Los Alamos National
Laboratory in Los Alamos, N.M.; and the Institute for the Study of
Earth, Oceans, and Space at the University of New Hampshire in
Durham.
Each Van Allen Probe carries an identical set of five instrument
suites that allow scientists to gather data on the belts in
unprecedented detail. The data are important for the study of the
effect of space weather on Earth, as well as fundamental physical
processes observed around other objects, such as planets in our solar
system and distant nebulae.
"Even 55 years after their discovery, the Earth's radiation belts
still are capable of surprising us and still have mysteries to
discover and explain," said Nicky Fox, Van Allen Probes deputy
project scientist at the Johns Hopkins University Applied Physics
Laboratory in Laurel, Md. "We thought we knew the radiation belts,
but we don't. The advances in technology and detection made by NASA
in this mission already have had an almost immediate impact on basic
science."
The Van Allen Probes are the second mission in NASA's Living With a
Star Program to explore aspects of the connected sun-Earth system
that directly affect life and society. Goddard manages the program.
The Applied Physics Laboratory built the spacecraft and manages the
mission for NASA.
For more information on the Van Allen Probes, visit:
http://www.nasa.gov/vanallenprobes
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